1. Field of the Invention
The present invention relates to an optical semiconductor package, and more particularly, to an optical package which is manufactured by the overmolding process.
2. Description of the Related Art
Referring to FIG. 1, it depicts a typically optical package 10 in prior art. The optical package 10 comprises a carrier or a substrate 12 and a chip 20 mounded on the substrate 12. The substrate 12 has a sidewall 16 which surrounds the substrate 12. A transparent lid 32 is mounted on the sidewall 16 by an adhesive 34 so as to form a hermetic cavity 30 and transmit the light interacting with the chip 20. The chip 20 has optical elements 22, such as optical sensors or imaging sensors, and is disposed in the cavity 30. The chip 20 is electrically connected to a plurality of bonding pads 18 of the substrate 12 by a plurality of bonding wires 26. The bonding pads 18 on the upper surface of the substrate 12 are electrically connected to the solder pads 14 on the bottom surface thereof through traces or vias 19. Because of the requirements of the manufacturing process, the substrate 12 is typically made of ceramal, i.e., the substrate 12 is a kind of ceramic substrate. Furthermore, the bonding pads 18 and the solder pads 14 are disposed on the upper surface and the bottom surface of the substrate 12, respectively, so the substrate 12 is a multilayer structure.
However, the multilayer ceramic substrate 12 has long delivery lead times and is substantially expensive. The bonding wires 26 are connected to the bonding pads 18 and the chip 20 which are recessed in the cavity 30, so the cavity 30 or the space surrounded by the sidewall 16 has to be large enough that the wire bond tool (not shown) can gain access to the bonding pads 18 and the chip 20. Therefore, the cost of the substrate 12 is further increased. The ceramic substrate 12 is supplied typically as single units or small arrays and hence is assembled in single units or small arrays, rather than large matrix arrays, so the assembly cost of the package 10 is further increased.
Accordingly, there exists a need for an optical package which can use a planar substrate and be mass-produced to reduce the manufacturing cost of the optical package.